Ya, you are too young for changes and you know your body best and what is normal and not. Your main concern is not as strong of an orgasm? They do say this happens as you get older but not in your 30's. It's kind of like how the eyesight goes a little over time as we age. Not a sudden change like you have after vacation. Who knows if your semen volume is the same, I agree with you, that's hard to judge. Here is a simple article that may help you. https://www.healthline.com/health/mens-health/weak-ejaculation#causes You seem well read so probably saw it. I also think if you had retrograde ejaculation, you'd be aware as you are self insightful. (is that a word? in tune with yourself is what I mean). When is the last time you had a physical? Hormones checked? When is your doctor's appointment?
The link GR provided covers most of the issues related to weak ejaculations, so that's a good place to start, a lot of good info there...
I'll just share a cpl things from personal experience that might be helpful: When I was around your age (mid-30s), I was experiencing something similar - what I perceived as relatively weak ejaculations (not much 'force' & somewhat decreased volume) & the sensation at orgasm was not as strong. Around that time, I was also experiencing some issues with the prostate - I had some discomfort in the perineal region, it was sometimes hard to find a comfortable position when sitting. Often the orgasm was weak & sometimes there was an unpleasant sensation at ejaculation, and sometimes urination was a little uncomfortable as well, almost like having a UTI, but not as severe. I saw my Dr. & was diagnosed with Prostatitis, which is a (usually) temporary inflammation of the gland. This is different from BPH - Prostate enlargement, which usually starts to affect guys in the their 40s, 50s & beyond. Prostatitis can be due to a bacterial infection or sometimes attributed to 'irregular' sexual activity - i.e., either infrequent ejaculations, too frequent or a mixture of the 2, for example, no activity for 10 days, then several times on a weekend. Dr's believe it's best for good Prostate health to have sort of a regular 'schedule' of ejaculation. Just be aware that sometimes Prostatitis can be very difficult to treat & can linger on & off for months or even a year or so. But in most cases, it resolves on its own sooner than that, and if this happens to be part of your issue, don't freak out if it doesn't clear up right away, just be patient & it probably will over time. Sometimes the Dr. will need to try a few different antibiotic types before it clears up.
This seems to commonly crop up in guys in their mid to late 30s, that's when it happened to me. I had a cpl friends around my age that also dealt with this issue, so it's not uncommon. I was on an antibiotic for a week or 10 days or so, it didn't seem to clear up right away, but eventually did. As mentioned, there's both a bacterial & non-bacterial form of Prostatitis. All during the time I was experiencing this, my orgasms were not too pleasurable & ejaculation force & volume were reduced. The good news is that I did recover & orgasms & ejaculation returned to normal. In recent years, I got back to very strong orgasms, altho ejaculate volume was reduced somewhat as a natural part of ageing.
So I think there's a reasonable chance this will clear up for you & things may return to normal. Obviously, I'd advise seeing your regular Dr. 1st (which you're already planning to do) & if that doesn't help, ask for a referral to a Urologist. Take heart - this may be only a temporary thing. You didn't mention discomfort in the perineal region, so this may not be what's causing your issue, but I think it's worth considering. It's possible the prostate is not functioning at an optimal level, such that it causes some of your symptoms, but not enough to result in discomfort. Good luck to you & please check back in later & let us know how you're doing...
My apologies for taking this long to respond. Long story short, over the following few days I felt I started to have a breakthrough in finding that things were getting back to normal, but I didn't want to jinx it. After letting time go by a little longer I feel like it's safe to say that things are indeed back to normal. I'm guessing somehow or another jet-lag must have been a factor, at least at first - and based on some following research sometimes anxiety from having such a thing happening once can start a bad cycle psychologically (i.e. worrying about the issue persisting can in fact, in itself, keep the issue going)
By the time my doctor appointment came around last week, I used it for other matters instead - one of them being arranging for my first physical.
My many thanks again for taking the time to write me, it did help in the interim knowing that there was a good possibility that my issue was temporary